Sept 9 - Abdominal, Back and Shoulder Region Flashcards
Name the two main groups of abdominal muscles
Anterior abdominal wall in front of the column (flexion).
Posterior abdominal wall behind the column (extension).
What is the importance of abdominal muscles?
They’re stabilizers that support the trunk and lower back
What function do the anterior abdominal muscles serve?
They serve a protective function
They cause movement of the trunk
They allow for changes in size of the cavity
Anterior abdominal muscles are innervated by:
intercostal nerves
Name the four anterior abdominal muscles
External abdominal oblique
Internal abdominal oblique
Transverse abdominal muscle (transversalis)
Rectus abdominus muscle
Describe the external abdominal oblique
It’s the outer most muscle on the anterior wall
It pushes pressure from the front inwards
Describe the internal abdominal oblique
It runs perpendicular to the external to the external oblique
It’s deep to external oblique
It functions with the external oblique to power “same side rotation”
Describe the transverse abdominal muscle
It connects the ribcage and pelvic bone
It forms a front platform
It flattens the lordotic curve of the spine
It stabilizes the anterior abdominal wall
Describe the rectus abdominus muscle
Most superficial pair of muscles run up either side of the mid-line of the abdomen
Identified by their bulging segments created by connective tissue divisions called Tendinous
Divides muscle into 4 sections (8-pack)
Name the three posterior abdominal wall muscles
Erector spinae
Iliacus muscle
Psoas major muscle
Describe the erector spinae group
Large column of muscle on either side of the vertebral column
Important for extension of the spine, but it also works against gravity to control trunk flexion (bending over)
It is often described as a single muscle, but it comprised of three muscles
Name the three muscles comprising the erector spinae group
Iliocostalis
Longissimus
Spinalis
Describe the quadratus lumborum
It powers lateral flexion of the lumbar spine
Stabilizes the twelfth rib against the action of the diaphragm during inspiration
What is the iliopsoas?
The term that refers to the psoas major and the iliacus. It was given because they share a common tendon.
Desribe the iliopsoas
The psoas major and iliacus muscles are deep to the abdominal contents adjacent to the vertebral column and within the pelvic cavity. Together they power hip flexion and are innervated by the femoral nerve. They also stabilize the back (important for climbing stairs)
What is the rule of 3, regarding the shoulder girdle
It is comprised of 3 bones, 3 joints and 3 ligaments.
What is the role of the shoulder girlde
It represents the only attachment of the appendicular skeleton (arm) to the axial skeleton (trunk)
Name the three bones of the shoulder girlde
Clavicle (aka the collar bone)
Scapula (aka the shoulder blade)
Humerus (aka the arm)
Describe the clavicle
Superficial, “S” shaped bone that acts like a strut (keeps shoulders back and arms at side). Medial third is convex, lateral third is concave (anteriorly).
It defines the broadness of shoulders.
Functions: force absorption, dissipation of force & rotation of the scapula in abduction
Describe the scapula
Spade-like, broad based bone. It’s thin, flat, triangular with 3 borders
There is NO attachment to chest wall
It’s held against the ribs by muscles
Name the three borders that comprise the scapula
The medial border runs along the vertebral column
The lateral border
The superior border
What is the acromiom process?
It’s the most lateral section of the scapula
It’s the part that’s in direct contact with the clavicle - forms a joint called the AC joint
What is the glenoid fossa?
Part of the scapula that articulates with the humerus - forms the shoulder joint aka GH joint
Describe the humerus
It’s a typical long bone (shaft and 2 enlarged ends)
The proximal end (aka head of the humerus) articulates with the glenoid fossa of the scapula (only about one third of the head is in contact with the scapula)
Name the three joints of the shoulder girlde
The sternoclavicular joint (SC joint)
The acromioclavicular joint (AC joint)
The gleno-humeral joint (GH joint aka shoulder joint)
Describe the sternoclavicular joint
It’s between the medial clavicle and clavicular notch of the sternum
It’s a synovial joint - saddle type
Movement occurs in a multi axial plane
Important for assessory motions
Give examples of assessory motions
Rolling, spinning, gliding, translatioj
Describe the arcromioclavicular joint
Palpable, rounded eminence on lateral shoulder (point of the shoulder)
Lateral clavicle articulates with acromion process (spine of scapula)
Plane type synovial joint supported by thick ligaments
It allows for the rotation of clavicle on acromion.
This is where should “separations” occur
Describe the gleno-humeral joint
Articulation between head of humerus and glenoid of scapula
Multi-axial ball & socket type synovial joint
Freely movable but structurally unstable because very little of humeral head (1/3rd) is in contact with fossa at any one time
Glenoid is deepened by a fibrocartilaginous ring (labrum) and stabilized by strong ligaments by increasing contact area
Describe the movements, as well as the planes in which they move, of the GH joint
Flexion and extension (sagittal plane)
Abduction and adduction (coronal plane)
Medial and lateral (transverse plane)
Describe scapulothoracic articulation
It’s not a true joint because the scapula is not attached by ligaments to the thoracic cage but rather is free floating within a complex of muscle attachments.
It’s responsible for overhead activity.
There is 1° of scapular movement for every 2° of GH movement
Describe scapulhumeral rhythm
Movement of the scapula relative to movement of the humerus
1° of scapular movement for every 2° of GH movement.
Abduction: 60% of GH joint, 40% of ST joint
Name the three movements of the shoulder girdle
Elevation/Depression
Protraction/Retraction
Horizontal Abduction/Adduction
What is circumduction
A composite movement (a bunch of movements added together)
Name the three types of muscles acting on the shoulder girdle
Thorax to humerus
Thorax to scapula/clavicle
Scapula/clavicle to humerus
Name the two thorax to humerus muscles
Latissimus dorsi
Pectoralis major
Describe the pectoralis major
Large, superficial muscle of the chest that forms the anterior wall of axilla
Has 2 heads: clavicular head, which attaches to the medial, anterior clavicle, and sternal head, which attaches to sternum and costal cartilages of first 6 ribs
Innervated by lateral and medial pectoral nerves
Name the functions of pectoralis major
Functions to power should flexion, adduction and medial rotation (ie. bear hug)
It can break your fall (reverse pushup)
Describe the latissimus dorsi
Large, superficial, broad, diamond shaped muscle of the back
Forms posterior wall of axilla
Arises from thoracolumbar fascia of low back, inserts proximal humerus
Innervated by thoracodorsal nerve
Name the functions of latissimus dorsi
Involved in shoulder extension
Secondary motions: medial rotation, adduction
Name the five thorax to scapula/clavicle muscles
Trapezius Rhomboid major & minor Serratus anterior Pectoralis minor Sternocleidomastoid
Describe the trapezius
Large, superficial, triangular muscle that runs from base of the skull all the way down to middle of spine and extends to outer edge of accromium
It acts on the scapula, not the shoulder joint
There are three sections: upper section (neck), middle fibres and lower fibres
Name the function of the trapezius, by section
The upper section is responsible for scapular elevation/rotation, as well as side flexion (unilateral) or extension (bilateral)
The middle section is responsible for scapular retraction
The lower section is responsible for pulling the medial end of the scapular spine down, rotating glenoid fossa upward and it is important to facilitate raising the arm over head
Describe the rhomboid major and minor. What are their functions
Deep to trapezius. It runs from vertebral column to scapula. It runs obliquely down and laterally.
It is innverated by dorsal scapular nerve.
It functions to retract the scapula
Minor is superior to major
Describe serratus anterior
“Serrated” digitations on side of chest
Extends from chest to vertebral border of scapula, running between thorax & scapula
Innervated by long thoracic nerve
Name the functions of serratus anterior
Protracts scapula, and functions to stabilize scapula to posterior wall of thorax (prevents winging of scapula)
Describe the pectoralis minor. Name its functions
Positioned deep to pectoralis major muscle
Actively protracts of scapula (powers reach beyond reach)
Innervated by the medial pectoral nerve
Describe sternocleidomastoid
Heavy cord like muscle on lateral aspect of the neck
Innervated by accessory nerve (CN XI)
Name the functions of sternocleidomastoid
Diverse functions:
- contract together (left and right): head and neck flexion
- contract unilaterally: tilts chin up and rotates to the opposite side
Name the two scapula/clavicle to humerus muscles
Deltoid Rotator cuff (SITS) muscles
Name the four rotator cuff muscles
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Describe the deltoid
Round muscle on top of shoulder, provides bulk of shoulder
Forms “U” around the shoulder - 3 distinct heads: anterior, middle, posterior
Innervated by axillary nerve
Name the functions of the 3 heads of the deltoid
Anterior: shoulder flexion
Middle: shoulder abduction
Posterior: shoulder extension
Describe the rotator cuff
Intrinsic muscles of shoulder that are critical for GH joint stability
Comprised of four separate muscles (SITS) to originate from scapula to attach to superior humerus
Name the function of the SITS muscles
Supraspinatus: abduction of shoulder
Infraspinatus: lateral rotation of shoulder
Teres minor: lateral rotation of shoulder
Subscapular: medial rotation of shoulder
